Achieving high power densities in Li-ion batteries requires increasing the charge and discharge rates. The two principal transport properties limiting these rates are the slow solid-state diffusion of Li-ions into the negative and positive electrodes and the slow diffusion between the electrodes. Slow solid-state diffusion processes within electrodes, may be mitigated by decreasing the features of both electrodes to the nanoscale, and the electrode morphologies of choice having high surface-to-volume ratios such as nanoparticles and nanowires. Although reducing the battery electrode features to the nanoscale has resulted in incremental improvements, decreasing the characteristic Li-ion diffusion length between the electrodes while maintaining the micro-nanoscale electrode morphology has not, and thus three-dimensional (3D) battery morphologies have been proposed. To fabricate a solid-state 3D Li-ion battery cell, an appropriate electrode material is deposited on a 3D current collector, the architecture of the current collector, which can be tailored, establishing the overall cell morphology and is the building block of the other cell components. A tailorable architecture provides the ability to tune the cell properties for specific applications based on performance metrics such as cost, power density, energy density, safety, and cell life.
In 3D architectures, interdigitated electrodes are separated by a thin conformal solid-state electrolyte onto which electrolyte one of the electrodes is directly applied, and require fabrication control such that a uniform, thin, and pinhole free electrolyte coating is generated. Electrodeposition provides a suitable coating process for such solid state electrolyte materials, since it is well understood, permits control of thickness, provides uniform coatings on complex and 3D surfaces, and has been demonstrated to be cost effective.